Catalysts are used to facilitate and speed up reactions. In some applications, it is desirable to utilize small-scale catalyst material, such as catalytic nano-sized particles. Furthermore, it is also oftentimes desirable to use support structures to provide a substructure upon which the catalytic particles can reside.
In FIG. 1A, catalyst 100 comprises a plurality of support particles 110a-d, each having at least one corresponding catalytic particle 120a-d. Although FIGS. 1A-C show only four support particles 110, it is contemplated that the catalyst 100 can comprise any number of support particles 110. The catalytic particles 120a-d can be chemically absorbed or bonded onto the surface of the support particles 110a-d. However, the catalytic particles 120a-d are not permanently fixed to their bonded support particles 110a-d. Rather, they are able to move from one support particle 110 to another. For example, FIGS. 1A-B show catalytic particles 120b and 120c moving from their respective support particles 110b and 110c to adjacent support particles 110a and 110d, respectively, such that catalytic particles 120a and 120b are disposed on support particle 110a and catalytic particles 120c and 120d are disposed on support particle 110d. In high temperature applications, the movement of these catalytic particles is magnified. As seen in FIG. 1C, as catalytic particles 120b and 120c move to neighboring support particles 110a and 110d, they begin to coalesce with other catalytic particles 120a and 120d on those neighboring support particles, resulting in larger catalytic particles 120ab and 120cd. 
It is understood that the effectiveness and activity of a catalyst are directly proportional to the size of the catalytic particles on the surface of the support particles. As the catalytic particles coalesce into larger clumps, the catalytic particle sizes increase, the surface area of the catalytic particles decreases, and the effectiveness of the catalyst is detrimentally affected.